1. Field of the Invention
The present invention relates to a method for manufacturing a laminated iron core by rotating and laminating a plurality of block iron cores respectively formed by laminating a plurality of iron core pieces blanked from a thin plate workpiece using a die, in a place (that is, the outside of the die) different from a location of the die, and an apparatus for manufacturing the laminated iron core.
2. Description of the Related Art
A laminated iron core is formed by laminating plural iron core pieces blanked from a thin plate workpiece. Since this thin plate workpiece has a plate thickness deviation, each of the iron core pieces is rotated by a given angle and then is laminated (so-called rotated and laminated) to thereby eliminate the plate thickness deviation of the thin plate workpiece.
For example, JP-A-2011-156585 as Patent Literature 1 discloses rotation and lamination, and this can improve accuracy of dimensions such as squareness or parallelism of the laminated iron core, with the result that the rotation and lamination are very effective as a method for improving motor characteristics.
An apparatus (rotating and laminating apparatus) for performing the rotation and lamination includes a case (so-called rotation and lamination inside a die) of being incorporated into a blanking die (hereinafter simply also called a die) for manufacturing the iron core piece, and a case (so-called rotation and lamination outside the die) of being installed outside the blanking die.
In the latter case, the iron core piece is blanked and formed by the blanking die, and a laminated body (hereinafter called a block iron core) laminated in any lamination thickness is ejected to the outside of the die and then, each of the block iron cores is rotated and laminated in a step separate from blanking.
The iron core piece located in the lowermost layer of each of the block iron cores is provided with only a through hole (caulking through hole) for reducing interference of a caulking protrusion formed for the purpose of mutually fixing the iron core pieces adjacent in a lamination direction. Accordingly, each of the block iron cores can be rotated and laminated smoothly.
After the rotation and lamination described above, for a stator iron core, each of the block iron cores is mutually fixed by welding and also, for a rotor iron core, a step of filling a magnet-insert hole with a resin with each of the block iron cores stacked is had, with the result that each of the block iron cores is mutually fixed using a binding force by the resin.
As a laminated iron core formed by laminating plural block iron cores, JP-A-11-55906 as Patent Literature 2 discloses a laminated iron core constructed of plural block iron cores (CB1 to CB5) formed by respectively laminating two or more kinds of iron core pieces with different shapes.
In the laminated iron core constructed in this manner, each of the plural block iron cores (CB1 to C135) must satisfy a management value of a lamination thickness (lamination height of the iron core pieces), with the result that the lamination thickness of each of the block iron cores is inspected, and each of the block iron cores is rotated and laminated using the block iron core satisfying the management value of the lamination thickness.
Patent Literature 1 JP-A-2011-156585
Patent Literature 2: JP-A-11-55906